Showing papers in "Vehicle System Dynamics in 2000"
TL;DR: In this article, a mathematical model for the steering control of an automobile is described, which is based on linear optimal discrete time preview control theory, but it is non-linear.
Abstract: A mathematical model for the steering control of an automobile is described. The structure of the model derives from linear optimal discrete time preview control theory but it is non-linear. Its parameter values are obtained by heuristic methods, using insight gained from the linear optimal control theory. The driver model is joined to a vehicle dynamics model and the path tracking performance is demonstrated, using moderate manoeuvring and racing speeds. The model is shown to be capable of excellent path following and to be robust against changes in the vehicle dynamics. Application to the simulation of manoeuvres specified by an ideal vehicle path and further development of the model to formalise the derivation of its parameter values and to put it to other uses are discussed.
264 citations
TL;DR: In this paper, a non-linear motion cueing algorithm was developed to anticipate and reduce these false motion cues in the Renault Dynamic Simulator, which is capable of directly rendering transient vehicle accelerations and sustained linear acceleration cues.
Abstract: Motion cueing in a driving simulator is necessary for advanced studies requiring drivers to accurately perceive and control the motion of their vehicle. The Renault Dynamic Simulator uses a 6-axes electro-mechanical mobile platform with an adequate motion control software. The physical and perceptual validity of the motion cueing is analyzed with respect to actual vehicle acceleration data and human self-motion per-ception criteria. Within the actuator displacement limits, it is capable of directly rendering transient vehicle accelerations whereas sustained linear acceleration cues are simulated by a coordinated platform tilt. Accel-eration transients are extracted by high-pass filtering, but a classical implementation based on linear filters may produce artifacts in some key driving situations. A non-linear motion cueing algorithm was developed to anticipate and reduce these false motion cues.
146 citations
TL;DR: In this paper, an extended (nonlinear) Kalman filter is designed to estimate the rapidly varying handling state vector, which is augmented to include adaptive states (cornering stiffnesses) to compensate for tyre force nonlinearities.
Abstract: This paper considers a method for estimating vehicle handling dynamic states in real-time, using a reduced sensor set; the information is essential for vehicle handling stability control and is also valuable in chassis design evaluation. An extended (nonlinear) Kalman filter is designed to estimate the rapidly varying handling state vector. This employs a low order (4 DOF) handling model which is augmented to include adaptive states (cornering stiffnesses) to compensate for tyre force nonlinearities. The adaptation is driven by steer-induced variations in the longitudinal vehicle acceleration. The observer is compared with an equivalent linear, model-invariant Kalman filter. Both filters are designed and tested against data from a high order source model which simulates six degrees of freedom for the vehicle body, and employs a combined-slip Pacejka tyre model. A performance comparison is presented, which shows promising results for the extended filter, given a sensor set comprising three accelerometers only. The study also presents an insight into the effect of correlated error sources in this application, and it concludes with a discussion of the new observer's practical viability.
142 citations
TL;DR: In this paper, the authors proposed a new tipover stability measure called the Force-Angle stability measure which has a simple geometric interpretation, is easily computed, and is sensitive to changes in Center of Mass height.
Abstract: .SUMMARY Mobile manipulators operating in field environments will be required to apply large forces, or manipulate large loads, and to perform such tasks on uneven terrain which may cause the system to approach, or reach, a dangerous tipover instability. To avoid tipover in an automatic system, or to provide a human operator with an indication of proximity to tipover, it is necessary to define a measure of available stability margin. This work presents a new tipover stability measure the Force-Angle . stability measure which has a simple geometric interpretation, is easily computed, and is sensitive to changes in Center of Mass height. The proposed metric is applicable to systems subject to inertial and external forces, operating over even or uneven terrains. Requirements for computation and implementation of the measure are described, and several different categories of application of the measure are presented along with useful normalizations. Performance of the Force-Angle measure is demonstrated and compared with that of other stability margin measures using a forestry vehicle simulation. Results show the importance of considering both center-of-mass height and system heaviness, and confirm the effectiveness of the Force-Angle measure in monitoring the tipover stability margin.
128 citations
TL;DR: In this article, the damper model structure is elaborated together with some measurement and estimation techniques to retrieve the model parameters, possibly from dynamometer measurements only, illustrated on a shock absorber normally used on the front suspension of a BMW series 7.
Abstract: For purpose of simulation of vehicle dynamics, a physical model of an automotive shock absorber has been developed and implemented in several software packages for multibody simulations. In the present paper, the damper model structure is shortly elaborated together with some measurement and estimation techniques to retrieve the model parameters, possibly from dynamometer measurements only. These techniques are illustrated on a shock absorber normally used on the front suspension of a BMW series 7.
120 citations
TL;DR: In this article, a formal method for the evaluation of the minimum time vehicle manoeuvre is described, where the problem is treated as one of Optimal Control and is solved using a direct transcription method.
Abstract: A formal method for the evaluation of the minimum time vehicle manoeuvre is described The problem is treated as one of Optimal Control and is solved using a direct transcription method The resulting Non Linear Programming problem is solved using a Sequential Quadratic Programming (SQP) algorithm for constrained minimisation of a multivariable function The optimisation program is used to investigate the effect of the yaw moment of inertia on vehicle performance in a double lane change manoeuvre The method is shown to have excellent capabilities to predict the vehicle maximum performance in transient conditions and to perform sensitivity analysis The influence of yaw inertia on the minimum manoeuvre time is found to be surprisingly small The extension of the method to larger problems, eg, lap time simulation, is also discussed
109 citations
TL;DR: In this paper, the effects of non-linear contact on the wheel/rail dynamic interaction are investigated through calculations, analysis and comparisons with the results from a linear contact model, and the difference between the nonlinear and linear interactions is found to be small if the roughness level is not extremely severe and a typical static contact preload exists.
Abstract: A study is presented of the non-linear dynamic interaction between a wheel and rail, excited by rough-ness on the wheel and rail contact surfaces. A moving irregularity model is used to represent the wheel/ rail interaction process in the time-domain. A low order multiple degree-of-freedom system is developed to approximate the infinite track for numerical simulations. The effects of the non-linear contact on the wheel/rail dynamic interaction are investigated through calculations, analysis and comparisons with the results from a linear contact model. The difference between the non-linear and linear interactions is found to be small if the roughness level is not extremely severe and a typical static contact preload exists. The difference increases for low preloads or for high roughness amplitudes. For example, if the wheel and rail surfaces are in good condition (r.m.s. amplitudes of roughness below 15 mm), the linear model can be used without significant error for all static loads down to 25 kN (equivale...
99 citations
TL;DR: In this paper, a nonlinear controller can focus on maximizing passenger comfort when the suspension deflection is small compared to its structural limit, which results in superior ride quality over the range of road surfaces, as well as reduced wear of suspension components.
Abstract: Nonlinear suspension controllers have the potential to achieve superior performance compared to their linear counterparts. A nonlinear controller can focus on maximizing passenger comfort when the suspension deflection is small compared to its structural limit. As the deflection limit is approached, the controller can shift focus to prevent the suspension deflection from exceeding this limit. This results in superior ride quality over the range of road surfaces, as well as reduced wear of suspension components. This paper presents a novel approach to the design of such nonlinear controllers, based on linear parameter-varying control techniques. Parameter-dependent weighting functions are used to design active suspensions that stiffen as the suspension limits are reached. The controllers use only suspension deflection as a feedback signal. The proposed framework easily extends to the more general case where all the three main performance metrics, i.e., passenger comfort, suspension travel and road holding ...
99 citations
TL;DR: In this paper, a 94 degrees of freedom non-linear multi-body dynamics model of a vehicle comprising front and rear suspensions, steering system, road wheels, tyres and vehicle inertia is presented.
Abstract: This paper presents a 94 degrees of freedom non-linear multi-body dynamics model of a vehicle comprising front and rear suspensions, steering system, road wheels, tyres and vehicle inertia. The model incorporates all sources of compliance: stiffness and damping, all with non-linear characteristics. The model is used for the purpose of vehicle handling analysis. A simulation run, pertaining to a double lane change is undertaken in-line with the ISO 3888 standard.
84 citations
TL;DR: In this paper, a block diagram representation of both conventional wheelsets and wheelsets with independently-rotating wheels is developed, with the objective of giving insights from a control engineering viewpoint for studies of actively-controlled wheelsets.
Abstract: Block diagram representations of both conventional wheelsets and wheelsets with independently-rotating wheels are developed, with the objective of giving insights from a control engineering viewpoint for studies of actively-controlled wheelsets. The analysis predicts a quasi-kinematic oscillation with independently-rotating wheels which has not been reported before. It also identifies possibilities for control approaches which might be used to stabilise a wheelset without affecting steady-state curving performance.
68 citations
TL;DR: In this paper, an active pantograph for high speed trains is proposed based on extensive simulation tests, where the model is modified by adding a wire actuation, in order to exert a constant contact force between the moving pantograph and the overhead contact wire.
Abstract: In this paper an innovative active pantograph for high-speed trains is proposed. The results presented are based on extensive simulation tests. The parameters used in the simulation are those of a real pantograph for high-speed trains: the pantograph model is modified by adding a wire actuation, in order to exert a constant contact force between the moving pantograph and the overhead contact wire. A wire-actuated control and contact force observers are proposed as effective solutions in the case of a possible implementation.
TL;DR: In this article, the authors develop a framework using mechanical multi-port networks to study the performance capabilities and constraints in vehicle suspensions. And they identify necessary conditions on the external behaviour of a quarter-car model for the suspension to be capable of passive realisation, and thereby establish that several behaviours or force laws cannot be implemented without an internal power source.
Abstract: This paper develops a framework using mechanical multi-port networks to study the performance capabilities and constraints in vehicle suspensions. We seek to understand the set of dynamic responses which are achievable for both passive and active systems. To this end, we view a suspension system as a mechanical multi-port network and draw on concepts from electrical circuits such as passivity and reciprocity. We identify necessary conditions on the external behaviour of a quarter-car model for the suspension to be capable of passive realisation, and thereby establish that several behaviours or force laws cannot be implemented without an internal power source. We study the number of available degrees of freedom (i.e., independently specifiable impedances) in the quarter-, half- and full-car cases.
TL;DR: In this paper, two nonlinear lateral control algorithms are designed for a tractor-semitrailer type commercial heavy vehicle to enhance the lateral stability and furthermore reduce tracking errors of the trailer.
Abstract: Two nonlinear lateral control algorithms are designed for a tractor-semitrailer type commercial heavy vehicle. The baseline steering control algorithm is designed utilizing input-output linearization. To enhance the lateral stability and furthermore reduce tracking errors of the trailer, braking forces are independently controlled on the inner and outer wheels of the trailer. The coordinated steering and braking control algorithm is designed based on the multivariable backstepping technique. Simulations conducted using the complex model show that the trailer yaw errors under coordinated steering and independent braking force control are much smaller than those without independent braking force control.
TL;DR: In this article, the authors deal with the experimental characterisation of the frequency dependent behaviour of elastomeric track components and with the definition of appropriate models in time domain for these elements.
Abstract: The paper deals with the experimental characterisation of the frequency dependent behaviour of elastomeric track components and with the definition of appropriate models in time domain for these elements. It is shown in particular that the dynamic stiffness of elastomeric components depends on both amplitude and frequency of deformation. Moreover, the dissipative behaviour is closer to the hysteretic hypothesis than to the viscous one. Some simple models allowing to reproduce the measured behaviour of these elements are defined and a procedure for the identification of their parameters is set-up. It is shown that rather simple models can provide better results than the classical ones composed by a spring in parallel to a viscous damper. It is also shown that the introduction of these models into a finite element description of the track provides a significant improvement in the calculation of track inertance and on the results of the simulation of train-track interaction.
TL;DR: In this article, a modal control strategy for the active steering of solid axle railway vehicles is presented, which reveals benefits of actively stabilizing the wheelsets of a railway vehicle.
Abstract: This paper presents the development of a modal control strategy for the active steering of solid axle railway vehicles and reveals benefits of actively stabilising the wheelsets of a railway vehicle. A modal decomposition is applied to a 2-axle railway vehicle to de-couple its body lateral and yaw motions and hence to allow more detailed analysis of the vehicle behaviour and more robust design of active controllers. Independent controllers for the two motions are developed based on the two de-coupled modes. Parameter variations such as creep coefficients and wheelset conicity are taken into account in the design process to guarantee a robust design. The study shows that, compared to a passive vehicle, the vehicles with actively steered wheelsets not only perform much better on a curved track, but also improve the ride quality on straight track. Computer simulations are used in the study to verify the development of the controllers and assess the system performance with the control scheme proposed.
TL;DR: The following paper describes a general conception and realization of a computer package to predict some aspects of dynamic behaviour of railway vehicles and MATLAB was used as environment for the realization.
Abstract: The following paper describes a general conception and realization of a computer package to predict some aspects of dynamic behaviour of railway vehicles. The package consists of three parts, an interactive pre-processor, the analysis program and an interactive post-processor. MATLAB was used as environment for the realization of the package. In recent versions only passenger vehicles, which have a MD 52 (Minden-Deutz) type trucks, can be analysed but the pre- and post-processor have a general form.
TL;DR: In this article, a methodology is presented for identifying car parameters by studying the vehicle's handling, based on the Kalman filter and makes it possible to determine the parameters on the basis of the results obtained from standard, on-road handling manoeuvres.
Abstract: A methodology is presented for identifying car parameters by studying the vehicle's handling The methodology is based on the Kalman filter and makes it possible to determine the parameters on the basis of the results obtained from standard, on-road handling manoeuvres
TL;DR: In this paper, a full car roll model is used to show an anti-roll control like that in Citroen's Xantia Activa and the proposed active roll with an in-series active suspension.
Abstract: Full car roll model is used to show an anti-roll control like that in Citroen's Xantia Activa and the proposed active roll with an in-series active suspension. Computed responses to pulse-shaped anti-phase road unevenness as well as to lateral acceleration in comparison with passive suspension are given in the paper. Also stability values for all parameters can be found.
TL;DR: In this paper, a differential braking control strategy using yaw rate feedback, coupled with µ feedforward, is introduced for a vehicle cornering on different µ roads, and a nonlinear 4-wheel car model is developed.
Abstract: A differential braking control strategy using yaw rate feedback, coupled with µ feedforward is introduced for a vehicle cornering on different µ roads. A nonlinear 4-wheel car model is developed. A desired yaw rate is calculated from the reference model based on the driver steering input. It is shown that knowledge of µ offers significant improvement of the vehicle desired trajectory over that of a yaw rate controller alone. Uncertainties and time delay in estimating µ are shown to still yield a system that is superior to using no µ information at all.
TL;DR: In this article, a mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analyzed and the effects of braking torque amplitude and time constant are discussed and the problems of lockup and loss of contact of the rear wheel are highlighted.
Abstract: A mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analysed. The effects of braking torque amplitude and time constant are discussed and the problems of lock-up and loss of contact of the rear wheel are highlighted. The suspensions' vibrations during braking are analysed by means of modal analysis. An optimisation method is developed in order to find the braking torque and the suspension parameters that minimise the stopping distance. The method takes the complete dynamic behaviour of the vehicle during braking into account and is based on a non-derivative minimisation algorithm. Several results are presented that show the possibility of shortening the stopping distance by optimum design of one or both of the suspensions.
TL;DR: In this paper, a bond graph representation of an independent suspension design was developed to study the energy flow through a vehicle, and the model was tuned and validated through experimental tests and was found to produce suitable results.
Abstract: Passive suspensions are designed to dissipate the energy otherwise transferred to a vehicle's body through interactions with a roadway or terrain. A bond graph representation of an independent suspension design was developed to study the energy flow through a vehicle. The bond graph model was tuned and validated through experimental tests and was found to produce suitable results. Examining the bond graph reveals that the dissipated energy associated with vertical and transverse coordinates generally originates from the longitudinal motion of the vehicle and is transferred through the tire-ground contact patch. Additionally, since the longitudinal energy originates from the vehicle's engine, the energy dissipated via the suspension shock absorber as well as other components (e.g., mechanical joints, etc.) essentially dissipate some engine energy. The plots presented in the paper support this theory by showing that upon traveling a rough terrain, the vehicle's longitudinal velocity drops more when vertical...
TL;DR: In this article, the effects of changing loading conditions on inertial properties of passenger cars have been found experimentally using a Vehicle Inertia Measurement Facility (VIMF) using simulation results using a vehicle handling model combined with a power steering system model and a nonlinear tire model.
Abstract: This paper uses simulation to investigate how vehicle loading conditions (driver only, passengers, cargo, and fuel) affect power steering system and overall vehicle dynamics. Our purpose of the study was to evaluate the power steering system model for possible use in the National Advanced Driving Simulator (NADS). The effects of changing loading conditions on inertial properties of passenger cars have been found experimentally using a Vehicle Inertia Measurement Facility (VIMF). This paper presents simulation results using a vehicle handling model combined with a power steering system model and a nonlinear tire model. A crucial part of this project was the adjustment of certain parameters of Pacejka's tire model in order to match simulation results with experimental measurements of vehicle and power steering variables in transient maneuvers.
TL;DR: In this paper, a two-degree-of-freedom loop shaping procedure is used to solve the problem of automatic vehicle steering using two-dimensional models. And the controller is split into two parts: the closed loop part achieves the robust stability requirement while the prefilter part processes the reference signal and achieves model matching.
Abstract: In this paper, the problem of automatic vehicle steering is addressed using a two-degree-of-freedom loop shaping procedure. The controller is split into two parts. The closed loop part achieves the robust stability requirement while the prefilter part processes the reference signal and is designed to achieve model matching. The whole synthesis procedure is emphasized and the controller is tested in various situations with several system parameter variations. The observer structure of the controller is finally exploited in order to consider scheduling controllers according to vehicle speed variations. The advantages of the controller scheduling are outlined with some simulation results.
TL;DR: In this paper, an overview of a theoretical study of an active seat suspension is provided, where an original feedback control command with a reversible electromechanical actuator is achieved, and the synthesis of the regulator is realized on the linearized model of the seat suspension and root locus method is employed.
Abstract: This paper provides an overview of a theoretical study of an active seat suspension. The principal objective of this study is to improve ride passenger comfort by reducing transmitted seat acceleration. The seat is represented by a non-linear two degree of freedom model. The system is linearized for small perturbations around the equilibrium. To control the dynamic of the seat suspension, an original feedback control command with a reversible electromechanical actuator is achieved. The synthesis of the regulator is realized on the linearized model of the seat suspension and the root locus method is employed. Stability and robustness characteristics have been studied. Numerical simulations in time and frequency domain show the interests of the regulator and its capability to isolate seat passenger.
TL;DR: In this article, a model of tire cornering properties using experimental modal parameters is studied. And the side force and lateral deformation under total adhesive and sliding conditions are obtained, and the calculated results tally well with the fitted results obtained using Magic Formula model.
Abstract: Modeling of tire cornering properties using experimental modal parameters is studied. With tire lateral experimental modal parameters, the distribution of side force and lateral deformation under total adhesive and sliding conditions are obtained. Side force, self-aligning, cornering stiffness and relaxation length under different loads and friction coefficients are also calculated. The calculated results are in correspondence to experimental results in the references qualitatively. The non-dimensional side force obtained from the calculated results is compared with the Fiala model, its modified expression by experiments and also the widely used empirical Magic Formula model. The calculated results tally well with the fitted results obtained using Magic Formula model. It can be seen that the tire steady state cornering model using experimental modal parameters proposed in this paper is better for an in-depth study of tire natural characteristics, and the labored experimental work can be avoided.
TL;DR: In this article, the steering and braking are automatically controlled to improve the performance of a vehicle in a very simple model of the vehicle, and the concept of minimizing the average radius of curvature of the path through controlling both driver inputs is shown to always be beneficial and worthwhile.
Abstract: When a driver is suddenly presented with an obstacle in his path, or realizes that his speed is too great for the curved road ahead, commonly he saturates both inputs of steering and braking and thereby jeopardizes his chances of successfully avoiding a collision or negotiating the turn. Although anti-lock braking systems (ABS) avoid saturation of the braking and steerability usually remains, there is evidence to suggest that the vehicle performance with this system could be greatly improved. Could the steering, in addition to the braking, be automatically controlled to improve the performance? Because these threatening situations are so variable, it is very difficult to find a controller which can override both driver inputs and is always beneficial. Using a very simple model of the vehicle, the concept of minimizing the average radius of curvature of the path through controlling both driver inputs is shown to always be beneficial, and worthwhile. The results also carry over to a more realistic model.
TL;DR: In this article, the dynamics of the contact between the pneumatic tire and the ground, in particular with reference to braking manoeuvres of aircraft, were analyzed in terms of transfer functions.
Abstract: This paper deals with the dynamics of the contact between the pneumatic tyre and the ground, in particular with reference to braking manoeuvres of aircraft. The transient response of the braking force is analytically evaluated in terms of the transfer functions that link the variation of the braking force to the variation of physical inputs affecting the interaction between the tread and the ground, in the longitudinal plane. The proposed models have been formulated in order to account for the effects of different reference conditions of steady braking on gains, zeros and poles of such transfer functions.
TL;DR: In this paper, the effect of the tire characteristics on the straight line motion of a vehicle is analyzed using a two degrees of freedom vehicle model and the results are confirmed from vehicle test and simulations with a more complex full-car model.
Abstract: In the dynamic simulation of vehicle straight line motion, a vehicle model usually drifts from its intended straight path even in the case of no external input. This is particularly true when a tire model based on experimental data is used. The purpose of this paper is to provide an enhancement of a basic understanding of a tire/vehicle system behavior in the straight line motion and to identify the effect of the tire on that motion. Through the analysis of a two degrees of freedom vehicle model, tire characteristic which causes a lateral drift in the straight line motion is identified. Then the results are confirmed from vehicle test and the simulations with a more complex full-car model.
TL;DR: In this article, the authors compared the dynamic behaviour of different configurations of radial and conventional two-axle bogies and found that the design parameters for better curve negotiation are not compatible with those for good stability.
Abstract: This article compares the dynamic behaviour of different configurations of radial and conventional two-axle bogies. In general, the design parameters for a better curve negotiation are not compatible with those for good stability. As the main target of this article is to compare the curving performances of different bogies under the same design basis, several bogie configurations with the same level of stability, obtained by choosing proper primary suspension stiffnesses, have been used. The comparison includes a conventional bogie and three radial bogies with differing self-steering and forced-steering principles in three different passenger services: High Speed, Regional and Mass Transit. The analysis has been concentrated on parameters such as stability, lateral wheel-track forces in curve and wheel wear indices. The results show that the radial bogie configurations studied do not make significant contributions in general applications with regard to a conventional bogie. It is only under specific runni...
TL;DR: In this article, a new nonlinear perturbation model on the cornering behavior of the tire is constructed and the nonlinear influences of tires on the steady-state steering behavior, dynamic response and handling stability of vehicle are discussed, applying the approximate analytical methods for nonlinear vibration.
Abstract: The problems of vehicle lateral dynamics based on nonlinear characteristics of tires are discussed in this paper. A new nonlinear perturbation model on the cornering behavior of the tire is constructed. The nonlinear influences of tires on the steady-state steering behavior, dynamic response and handling stability of vehicle are discussed, applying the approximate analytical methods for nonlinear vibration. An analytical criterion of stability is obtained. Some numerical examples are given.